JP6246875B1 - Measuring device - Google Patents

Abstract

A measuring apparatus capable of improving measurement accuracy and improving measurement efficiency. A measuring apparatus 1 performs z-direction on a part of z-position investigation areas preset in a predetermined measurement area of a workpiece W based on interference fringe images obtained by imaging systems 4A and 4B. Acquire complex amplitude data at a plurality of positions. Subsequently, a plurality of intensity images related to the z position survey region are acquired from the plurality of complex amplitude data, and a position in the z direction of the z position survey region is determined based on the plurality of intensity images. Then, complex amplitude data at this position is acquired for the entire measurement region, and three-dimensional measurement related to the measurement region is executed. [Selection] Figure 1

Description

  The present invention relates to a measuring device that measures the shape of an object to be measured.

  Conventionally, a measuring device using an interferometer is known as a measuring device that measures the shape of an object to be measured (see, for example, Patent Document 1). Among them, there is a measurement device that performs measurement by a phase shift method based on a plurality of interference fringe images having different phases (see, for example, Patent Document 2).

  However, unless the object to be measured is properly placed within the in-focus range of the imaging means, it is not possible to acquire focused image data with high accuracy, and there is a concern that measurement accuracy may be reduced.

  For this reason, conventionally, it is necessary to accurately perform pre-processing and the like for placing the object to be measured within the in-focus range before starting the measurement, and there is a possibility that the time required for the measurement becomes longer as a whole. Moreover, there is a possibility that the measurement range of the height measurement is restricted by the focus range.

  On the other hand, in recent years, an interference imaging apparatus or the like having a function of correcting the defocus aberration can be seen (see, for example, Patent Document 3). By correcting the defocus aberration, the image data in which the defocus is generated can be converted into the focused image data by the arithmetic processing, so that the image data with high accuracy can be acquired. As a result, measurement accuracy can be improved.

JP-A-8-219722 JP-A-11-337321 JP-T-2006-504947

  However, in the prior art according to Patent Document 3, aberration-corrected images are respectively created for a plurality of positions in the optical axis direction within a predetermined range in the optical axis direction (height direction) where the object to be measured can exist, and the focus is adjusted from the images. The image is extracted. That is, since it is necessary to create a plurality of aberration-corrected images obtained by performing the aberration correction process on the entire image obtained by the imaging unit, the processing load is extremely large, and the time required for the process may be increased. . As a result, the measurement efficiency may be significantly reduced.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a measuring apparatus capable of improving measurement accuracy and improving measurement efficiency.

  Hereinafter, each means suitable for solving the above-described problem will be described separately. In addition, the effect specific to the means to respond | corresponds as needed is added.

Means 1. The incident predetermined light is divided into two lights, one light can be irradiated as a measurement light to an object to be measured (for example, a wafer substrate), and the other light can be irradiated as a reference light to a reference surface. A predetermined optical system (specific optical system) that can be synthesized and emitted again,
Irradiating means capable of emitting predetermined light incident on the predetermined optical system;
Imaging means capable of imaging output light emitted from the predetermined optical system;
Measurement provided with image processing means capable of performing measurement according to a predetermined measurement region (entire area of the measurement object or a part thereof) based on the interference fringe image obtained by the imaging means A device,
The image processing means includes
Based on the interference fringe image obtained by the imaging means, the complex amplitude data at a predetermined position in the optical axis direction is determined at least within a predetermined range in the optical axis direction for a specific area preset in the measurement area. First data acquisition means for acquiring a plurality of data for each interval;
Image acquisition for acquiring a plurality of intensity (luminance) images for each predetermined interval for the specific region from a plurality of complex amplitude data for the predetermined region for the specific region acquired by the first data acquisition unit. Means,
Position determining means for determining a predetermined position in the optical axis direction (for example, the position where the most focused intensity image is obtained) based on the plurality of intensity images acquired by the image acquiring means;
Second data acquisition means for acquiring complex amplitude data at the position determined by the position determination means for the entire measurement region;
A measurement apparatus comprising: a measurement execution unit that executes measurement related to the measurement region based on the complex amplitude data acquired by the second data acquisition unit.

  In addition, the “predetermined optical system” includes not only “an optical system that outputs interference light after interfering the reference light and the measurement light” but also “the reference light and the measurement light without causing interference inside. Also, an “optical system that simply outputs as synthesized light” is included. However, when the “output light” output from the “predetermined optical system” is “combined light”, in order to capture the “interference fringe image”, at least before the imaging is performed by the “imaging unit”, The light is converted into “interference light” via a predetermined interference means.

  That is, for the purpose of causing interference of light (taking an interference fringe image), the incident predetermined light is divided into two lights, and one of the lights can be irradiated to the object to be measured as measurement light, and An optical system that can irradiate the reference surface with the other light as a reference light and that can synthesize and emit the light again can be referred to as an “interference optical system”. Therefore, in the above means 1 (the same applies to each of the following means), “predetermined optical system (specific optical system)” may be rephrased as “interference optical system”.

  According to the means 1, first, complex amplitude data at a plurality of positions in the optical axis direction is acquired not for the entire measurement region but only for a specific region (a limited narrow range) preset in the measurement region. Based on this, an optimum position that focuses on the object to be measured (specific area) is searched and determined. Thereafter, complex amplitude data for the entire measurement region at the position is acquired, and measurement related to the measurement region is performed.

  As a result, it is possible to reduce the load required for processing for acquiring data necessary for performing measurement related to the measurement region, and it is possible to reduce the time required for the processing. As a result, measurement accuracy can be improved and measurement efficiency can be improved.

  Examples of the “predetermined interval” include an interval of “focus range” and “measurement range” in the optical axis direction.

  Mean 2. 2. The measuring apparatus according to claim 1, wherein the position determining unit determines a position in the optical axis direction of the specific region based on the plurality of intensity images acquired by the image acquiring unit.

  According to the means 2, the position (height direction position) in the optical axis direction of the object to be measured (specific area) is specified, and the complex amplitude data of the entire measurement area at the position is acquired and measured. . As a result, more optimal and accurate data focused on the object to be measured (specific region) can be obtained compared to a configuration in which only optimal data is extracted from complex amplitude data acquired at a plurality of predetermined intervals. Can be acquired. As a result, the measurement accuracy can be further improved.

  Means 3. The measuring apparatus according to claim 2, wherein the specific region is a region serving as a reference when performing measurement in the optical axis direction related to the measurement region.

  According to the means 3, it is possible to perform measurement under more optimal and accurate data focused on a specific area serving as a measurement reference, and to further improve measurement accuracy.

  Means 4. 4. The measuring apparatus according to claim 1, wherein the specific area is set at a plurality of locations.

  According to the means 4, since there are a plurality of specific regions, it is easy to find a more optimal position where the complex amplitude data of the entire measurement region should be acquired.

  In addition, for example, when there is a height difference in the measurement area because the object to be measured is warped or tilted, the measurement is performed if only one specific area is set. There is a possibility that data focused on the entire area cannot be acquired.

  On the other hand, since there are a plurality of specific areas as in this means, a series of processes according to the above means 1 can be executed for each of the plurality of specific areas, and the data focused on the entire measurement area as a whole can be obtained. It can be acquired. For example, for the first area of the measurement area, the data at the first position in the optical axis direction is used, and for the second area, the data at the second position in the optical axis direction is used, thereby focusing on the entire measurement area. It is possible to acquire data that matches.

Means 5. Phase shift means for providing a relative phase difference between the reference light and the measurement light;
The image processing means includes
Predetermined measurement of the object to be measured based on a plurality of interference fringe images obtained by imaging the output light phase-shifted in a plurality of ways (for example, 3 or 4) by the phase-shift means. The measurement apparatus according to any one of means 1 to 4, wherein the measurement apparatus is configured to be able to execute measurement relating to a region.

Means 6. The irradiation means includes
First irradiating means capable of emitting first light including polarized light having a first wavelength, which is incident on the predetermined optical system;
A second irradiating means capable of emitting second light including polarized light of a second wavelength that is incident on the predetermined optical system;
The imaging means includes
First imaging means capable of imaging output light related to the first light emitted from the predetermined optical system by making the first light incident on the predetermined optical system;
And second imaging means capable of imaging the output light related to the second light emitted from the predetermined optical system when the second light is incident on the predetermined optical system. The measuring device according to any one of means 1 to 5.

  If two types of light having different wavelengths are used as in the above means 6, the measurement range can be expanded. As a result, when the first data acquisition unit acquires complex amplitude data related to a specific region at measurement range intervals, the processing load can be reduced.

  The “first light” emitted from the “first irradiating means” may be light including at least “polarized light of the first wavelength (first polarized light)”, and then cut in the “predetermined optical system”. It may be light including other extra components (for example, “non-polarized light” or “circularly polarized light”).

  Similarly, the “second light” emitted from the “second irradiation means” may be light including at least “polarized light of the second wavelength (second polarized light)”, and then in the “predetermined optical system”. It may be light (for example, “non-polarized light” or “circularly polarized light”) including other extra components to be cut.

  Further, the “output light related to the first light” output from the “predetermined optical system (specific optical system)” “the combined light of the reference light and the measurement light related to the first light, or the combined light interferes. "The output light related to the second light" includes "the combined light of the reference light and the measurement light related to the second light, or the interference light obtained by interfering with the combined light" .

  Mean 7 7. The measuring apparatus according to claim 1, wherein the object to be measured is a wafer substrate on which bumps are formed.

  According to the means 7, the bumps formed on the wafer substrate can be measured. As a result, in the bump inspection, it is possible to determine the quality of the bump based on the measured value. Therefore, in such an inspection, the effect of each means described above is exhibited, and the quality determination can be performed with high accuracy. As a result, it is possible to improve inspection accuracy and inspection efficiency in the bump inspection apparatus.

It is a schematic block diagram of a measuring device. It is a block diagram which shows the electric constitution of a measuring device. It is an optical path figure which shows the optical path of 1st light. It is an optical path figure which shows the optical path of 2nd light. It is a flowchart which shows the flow of a measurement process. It is explanatory drawing for demonstrating the positional relationship etc. of a workpiece | work and an image pick-up element. It is explanatory drawing for demonstrating the positional relationship etc. of a workpiece | work and an image pick-up element. It is a side surface schematic diagram which shows the wafer substrate in which the bump was formed. It is explanatory drawing for demonstrating the three-dimensional measurement of a bump. It is explanatory drawing for demonstrating the two-dimensional measurement of a bump.

  Hereinafter, an embodiment of a measuring apparatus will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating a schematic configuration of a measurement apparatus 1 according to the present embodiment, and FIG. 2 is a block diagram illustrating an electrical configuration of the measurement apparatus 1. In the following, for the sake of convenience, the front-rear direction in FIG. 1 will be referred to as the “X-axis direction”, the vertical direction in the paper will be referred to as the “Y-axis direction”, and the left-right direction in FIG.

  The measuring apparatus 1 is configured based on the principle of a Michelson interferometer, and includes two light projecting systems 2A and 2B (first light projecting system 2A and second light projecting system 2) as irradiation means capable of outputting light of a specific wavelength. A light projecting system 2B), an interference optical system 3 into which the light emitted from each of the light projecting systems 2A and 2B is incident, and two imaging means capable of imaging the light emitted from the interference optical system 3. Various types of control, image processing, arithmetic processing, and the like related to the imaging systems 4A, 4B (first imaging system 4A, second imaging system 4B), light projection systems 2A, 2B, interference optical system 3, imaging systems 4A, 4B, etc. And a control device 5 for performing the operation.

  Here, “control device 5” constitutes “image processing means” in the present embodiment, and “interference optical system 3” constitutes “a predetermined optical system (specific optical system)” in the present embodiment. In the present embodiment, for the purpose of causing light interference (taking an interference fringe image), the incident predetermined light is divided into two lights (measurement light and reference light), and the 2 An optical system that generates an optical path difference between two lights and then combines and outputs the light again is called an “interference optical system”. In other words, not only an optical system that causes two lights to interfere with each other and then outputs the light as interference light, but also an optical system that outputs only the combined light without causing the two lights to interfere with each other inside. It is called. Therefore, as will be described later in this embodiment, when two lights (measurement light and reference light) are output as combined light without interference from the “interference optical system”, at least a stage before imaging. Interference light is obtained through predetermined interference means (for example, inside the imaging system).

  First, the configuration of the two light projecting systems 2A and 2B (first light projecting system 2A and second light projecting system 2B) will be described in detail. The first light projecting system 2A includes a first light emitting unit 11A, a first optical isolator 12A, a first non-polarizing beam splitter 13A, and the like. Here, the “first light emitting unit 11A” constitutes the “first irradiation unit” in the present embodiment.

Although not shown, the first light emitting portion 11A includes a beam expander which emits linearly polarized light having a specific wavelength lambda ₁ laser light source and capable of outputting, as an enlarged linearly polarized light output from the laser light source parallel light, the intensity A polarizing plate for adjustment, a half-wave plate for adjusting the polarization direction, and the like are provided.

Under this configuration, in the present embodiment, linearly polarized light having a wavelength λ ₁ (for example, λ ₁ = 1500 nm) having a polarization direction in a direction inclined by 45 ° with respect to the X-axis direction and the Y-axis direction is emitted from the first light emitting unit 11A. The light is emitted leftward in the Z-axis direction. Here, “wavelength λ ₁ ” corresponds to “first wavelength” in the present embodiment. Hereinafter, the light of wavelength λ ₁ emitted from the first light emitting unit 11A is referred to as “first light”.

  The first optical isolator 12A is an optical element that transmits only light traveling in one direction (leftward in the Z-axis direction in the present embodiment) and blocks light in the reverse direction (rightward in the Z-axis direction in the present embodiment). Thereby, only the 1st light radiate | emitted from 11 A of 1st light emission parts will be permeate | transmitted, and the damage, destabilization, etc. of 1st light emission part 11A by a return light can be prevented.

  The first non-polarizing beam splitter 13A is a known cube-shaped optical member in which a right-angle prism (triangular prism having a right-angled isosceles triangle as a bottom surface; the same shall apply hereinafter) is bonded and integrated. 13Ah is coated with a metal film, for example. The “first non-polarizing beam splitter 13A” constitutes the “first light guiding unit” in the present embodiment.

  The same applies hereinafter, but the non-polarizing beam splitter divides incident light into transmitted light and reflected light at a predetermined ratio including the polarization state. In the present embodiment, a so-called half mirror having a division ratio of 1: 1 is employed. That is, the P-polarized component and S-polarized component of the transmitted light, and the P-polarized component and S-polarized component of the reflected light are all divided at the same ratio, and the polarization states of the transmitted light and reflected light are the polarization states of the incident light. Will be the same.

  In this embodiment, linearly polarized light having a polarization direction in a direction parallel to the paper surface of FIG. 1 (Y-axis direction or Z-axis direction) is called P-polarized light (P-polarized light component), and X perpendicular to the paper surface of FIG. Linearly polarized light whose axial direction is the polarization direction is called S-polarized light (S-polarized light component).

  Further, the first non-polarizing beam splitter 13A is arranged so that one of two surfaces adjacent to each other across the joint surface 13Ah is orthogonal to the Y-axis direction and the other is orthogonal to the Z-axis direction. That is, the joint surface 13Ah of the first non-polarizing beam splitter 13A is disposed so as to be inclined by 45 ° with respect to the Y-axis direction and the Z-axis direction. More specifically, a part (half) of the first light incident to the left in the Z-axis direction from the first light emitting unit 11A is transmitted to the left in the Z-axis direction through the first optical isolator 12A, and the remaining (half) is transmitted in the Y direction. It arrange | positions so that it may reflect in an axial direction downward.

  Similar to the first light projecting system 2A, the second light projecting system 2B includes a second light emitting unit 11B, a second optical isolator 12B, a second non-polarizing beam splitter 13B, and the like. Here, the “second light emitting unit 11B” constitutes the “second irradiation unit” in the present embodiment.

Similarly to the first light emitting unit 11A, the second light emitting unit 11B is a laser light source capable of outputting linearly polarized light having a specific wavelength λ ₂ or a beam extract that expands the linearly polarized light output from the laser light source and emits it as parallel light. A panda, a polarizing plate for adjusting the intensity, a half-wave plate for adjusting the polarization direction, and the like are provided.

Under this configuration, in the present embodiment, linearly polarized light having a wavelength λ ₂ (for example, λ ₂ = 1503 nm) having a polarization direction in a direction inclined by 45 ° with respect to the X-axis direction and the Z-axis direction is emitted from the second light emitting unit 11B. The light is emitted upward in the Y-axis direction. Here, “wavelength λ ₂ ” corresponds to “second wavelength” in the present embodiment. Hereinafter, the light having the wavelength λ ₂ emitted from the second light emitting unit 11B is referred to as “second light”.

  Similar to the first optical isolator 12A, the second optical isolator 12B transmits only light traveling in one direction (upward in the Y-axis direction in this embodiment) and blocks light in the reverse direction (downward in the Y-axis direction in this embodiment). It is an optical element. Thereby, only the 2nd light radiate | emitted from the 2nd light emission part 11B will be permeate | transmitted, and the damage, destabilization, etc. of the 2nd light emission part 11B by a return light can be prevented.

  Similar to the first non-polarizing beam splitter 13A, the second non-polarizing beam splitter 13B is a known cube-shaped optical member in which right-angle prisms are bonded together, and the joint surface 13Bh is made of a metal film or the like, for example. Coating is applied. The “second non-polarizing beam splitter 13B” constitutes the “second light guiding unit” in the present embodiment.

  The second non-polarizing beam splitter 13B is arranged so that one of two surfaces adjacent to each other across the joint surface 13Bh is orthogonal to the Y-axis direction and the other is orthogonal to the Z-axis direction. That is, the joint surface 13Bh of the second non-polarizing beam splitter 13B is arranged to be inclined by 45 ° with respect to the Y-axis direction and the Z-axis direction. More specifically, a part (half) of the second light incident upward from the second light emitting unit 11B through the second optical isolator 12B is transmitted upward in the Y-axis direction, and the remaining (half) is transmitted through Z. It arrange | positions so that it may reflect in the axial direction rightward.

  Next, the configuration of the interference optical system 3 will be described in detail. The interference optical system 3 includes a polarizing beam splitter (PBS) 20, quarter wave plates 21, 22, a reference surface 23, an installation unit 24, and the like.

  The polarization beam splitter 20 is a known cube-type optical member in which right-angle prisms are bonded together, and a coating such as a dielectric multilayer film is applied to the joint surface (boundary surface) 20h.

  The polarization beam splitter 20 divides incident linearly polarized light into two polarization components (P polarization component and S polarization component) whose polarization directions are orthogonal to each other. The polarization beam splitter 20 in the present embodiment is configured to transmit the P-polarized component and reflect the S-polarized component.

  The polarizing beam splitter 20 is disposed so that one of two surfaces adjacent to each other with the joint surface 20h interposed therebetween is orthogonal to the Y-axis direction and the other is orthogonal to the Z-axis direction. That is, the joining surface 20h of the polarizing beam splitter 20 is disposed so as to be inclined by 45 ° with respect to the Y-axis direction and the Z-axis direction.

  More specifically, the first surface 20a of the polarizing beam splitter 20 on which the first light reflected downward from the first non-polarizing beam splitter 13A enters the Y-axis direction (upper side surface in the Y-axis direction) 20a, and the first surface 20a. The third surface (Y-axis direction lower side surface) 20c opposite to each other is arranged so as to be orthogonal to the Y-axis direction. The “first surface 20a of the polarization beam splitter 20” corresponds to the “first input / output unit” in the present embodiment.

  On the other hand, the second surface of the polarizing beam splitter 20 that is adjacent to the first surface 20a and the bonding surface 20h and receives the second light reflected rightward in the Z-axis direction from the second non-polarizing beam splitter 13B. (Z-axis direction left side surface) 20b and a fourth surface (Z-axis direction right side surface) 20d opposite to the second surface 20b are arranged to be orthogonal to the Z-axis direction. The “second surface 20b of the polarization beam splitter 20” corresponds to the “second input / output unit” in the present embodiment.

  A quarter-wave plate 21 is disposed so as to face the third surface 20c of the polarization beam splitter 20 in the Y-axis direction, and the reference surface faces the quarter-wave plate 21 in the Y-axis direction. 23 is arranged.

  The quarter-wave plate 21 has a function of converting linearly polarized light into circularly polarized light and converting circularly polarized light into linearly polarized light. That is, linearly polarized light (reference light) emitted from the third surface 20 c of the polarization beam splitter 20 is converted into circularly polarized light via the quarter wavelength plate 21 and then irradiated to the reference surface 23. The reference light reflected by the reference surface 23 is again converted from circularly polarized light into linearly polarized light through the quarter wavelength plate 21 and then enters the third surface 20 c of the polarizing beam splitter 20.

  On the other hand, a quarter-wave plate 22 is disposed so as to face the fourth surface 20d of the polarization beam splitter 20 in the Z-axis direction, and the installation portion so as to face the quarter-wave plate 22 in the Z-axis direction. 24 is arranged.

  The quarter wavelength plate 22 has a function of converting linearly polarized light into circularly polarized light and converting circularly polarized light into linearly polarized light. In other words, the linearly polarized light (measurement light) emitted from the fourth surface 20 d of the polarization beam splitter 20 is converted into circularly polarized light via the quarter wavelength plate 22 and then the measurement object placed on the installation unit 24. The workpiece W is irradiated. The measurement light reflected by the workpiece W is again converted from circularly polarized light into linearly polarized light via the quarter wavelength plate 22 and then enters the fourth surface 20 d of the polarizing beam splitter 20.

  Next, the configuration of the two imaging systems 4A and 4B (first imaging system 4A and second imaging system 4B) will be described in detail. The first imaging system 4A includes a quarter wavelength plate 31A, a first polarizing plate 32A, a first camera 33A that constitutes a first imaging means, and the like.

  The quarter-wave plate 31A is for converting linearly polarized light (the reference light component and the measurement light component of the first light) that has passed through the second non-polarizing beam splitter 13B leftward in the Z-axis direction into circularly polarized light. is there.

  The first polarizing plate 32A selectively transmits each component of the first light converted into circularly polarized light by the quarter wavelength plate 31A. Thereby, the reference light component and measurement light component of the 1st light from which a rotation direction differs can be made to interfere about a specific phase. The “first polarizing plate 32A” constitutes “phase shift means” and “interference means” in the present embodiment.

  The first polarizing plate 32A according to the present embodiment is configured to be rotatable about the Z-axis direction as an axis, and is controlled so that the transmission axis direction changes by 45 °. Specifically, the transmission axis direction changes to “0 °”, “45 °”, “90 °”, and “135 °” with respect to the Y-axis direction.

  Thereby, the reference light component and measurement light component of the 1st light which permeate | transmit the 1st polarizing plate 32A can be made to interfere by four types of phases. That is, it is possible to generate interference light whose phases are different by 90 °. Specifically, interference light having a phase of “0 °”, interference light having a phase of “90 °”, interference light having a phase of “180 °”, and interference light having a phase of “270 °” can be generated. .

  The first camera 33A is a known camera including a lens, an image sensor 33Aa (see FIG. 6), and the like. In the present embodiment, a CCD area sensor is employed as the image sensor 33Aa of the first camera 33A. Of course, the image sensor 33Aa is not limited to this, and for example, a CMOS area sensor or the like may be employed. Moreover, it is preferable to use a telecentric lens as the lens.

  Image data captured by the first camera 33A is converted into a digital signal inside the first camera 33A, and then input to the control device 5 (image data storage device 54) in the form of a digital signal. Yes.

  Specifically, an interference fringe image having a phase “0 °”, an interference fringe image having a phase “90 °”, an interference fringe image having a phase “180 °”, and an interference fringe image having a phase “270 °” are associated with the first light. The image is picked up by the first camera 33A.

  Similar to the first imaging system 4A, the second imaging system 4B includes a quarter-wave plate 31B, a second polarizing plate 32B, a second camera 33B constituting the second imaging means, and the like.

  The quarter wavelength plate 31B is for converting the linearly polarized light (the reference light component and the measurement light component of the second light) transmitted through the first non-polarizing beam splitter 13A upward in the Y-axis direction into circularly polarized light. is there.

  Similar to the first polarizing plate 32A, the second polarizing plate 32B selectively transmits each component of the second light converted into circularly polarized light by the quarter wavelength plate 31B. Thereby, the reference light component and measurement light component of the 2nd light from which a rotation direction differs can be made to interfere about a specific phase. The “second polarizing plate 32B” constitutes “phase shift means” and “interference means” in the present embodiment.

  The second polarizing plate 32B according to the present embodiment is configured to be rotatable about the Y-axis direction as an axis, and is controlled so that the transmission axis direction changes by 45 °. Specifically, the transmission axis direction changes to “0 °”, “45 °”, “90 °”, and “135 °” with respect to the X-axis direction.

  Thereby, the reference light component and measurement light component of the 2nd light which permeate | transmit the 2nd polarizing plate 32B can be made to interfere by four types of phases. That is, it is possible to generate interference light whose phases are different by 90 °. Specifically, interference light having a phase of “0 °”, interference light having a phase of “90 °”, interference light having a phase of “180 °”, and interference light having a phase of “270 °” can be generated. .

  Similar to the first camera 33A, the second camera 33B is a known camera including a lens, an image sensor 33Ba (see FIG. 6), and the like. In the present embodiment, as with the first camera 33A, a CCD area sensor is employed as the image sensor 33Ba of the second camera 33B. Of course, the imaging element 33Ba is not limited to this, and for example, a CMOS area sensor or the like may be adopted. Moreover, it is preferable to use a telecentric lens as the lens.

  Similar to the first camera 33A, the image data captured by the second camera 33B is converted into a digital signal inside the second camera 33B and then sent to the control device 5 (image data storage device 54) in the form of a digital signal. It is designed to be entered.

  Specifically, an interference fringe image having a phase “0 °”, an interference fringe image having a phase “90 °”, an interference fringe image having a phase “180 °”, and an interference fringe image having a phase “270 °” related to the second light. The image is taken by the second camera 33B.

  Here, the electrical configuration of the control device 5 will be described. As shown in FIG. 2, the control device 5 includes a CPU and an input / output interface 51 that control the entire measurement device 1, an input device 52 as an “input unit” configured by a keyboard, a mouse, or a touch panel, a liquid crystal screen A display device 53 having a display screen such as a display device 53, an image data storage device 54 for sequentially storing image data captured by the cameras 33A and 33B, and a calculation result storage for storing various calculation results. A device 55 and a setting data storage device 56 for storing various information in advance are provided. Note that these devices 52 to 56 are electrically connected to the CPU and the input / output interface 51.

  Next, the operation of the measuring device 1 will be described. As will be described later, the irradiation of the first light and the second light in the present embodiment is performed simultaneously, and the optical path of the first light and the optical path of the second light partially overlap. Then, in order to make it easier to understand, each of the optical paths of the first light and the second light will be described individually using different drawings.

First, the optical path of the first light will be described with reference to FIG. As shown in FIG. 3, the first light of wavelength λ ₁ (linearly polarized light whose polarization direction is inclined by 45 ° with respect to the X-axis direction and the Y-axis direction) is emitted leftward in the Z-axis direction from the first light emitting unit 11A.

  The first light emitted from the first light emitting unit 11A passes through the first optical isolator 12A and enters the first non-polarizing beam splitter 13A. Part of the first light incident on the first non-polarizing beam splitter 13A is transmitted leftward in the Z-axis direction, and the rest is reflected downward in the Y-axis direction.

  Among these, the first light reflected downward in the Y-axis direction (linearly polarized light whose polarization direction is inclined by 45 ° with respect to the X-axis direction and the Z-axis direction) is incident on the first surface 20 a of the polarization beam splitter 20. On the other hand, the first light transmitted leftward in the Z-axis direction becomes discarded light without entering any optical system or the like.

  Here, if the light to be discarded is used for wavelength measurement or light power measurement as required, the measurement accuracy can be improved by stabilizing the light source.

  The first light incident downward from the first surface 20a of the polarization beam splitter 20 in the Y-axis direction transmits its P-polarized component downward in the Y-axis direction and is emitted from the third surface 20c as reference light, while its S The polarized component is reflected rightward in the Z-axis direction and is emitted from the fourth surface 20d as measurement light.

  The reference light (P-polarized light) related to the first light emitted from the third surface 20 c of the polarization beam splitter 20 is converted into clockwise circularly polarized light by passing through the quarter wavelength plate 21, and then the reference surface 23. Reflect on. Here, the rotation direction with respect to the traveling direction of the light is maintained. Thereafter, the reference light related to the first light passes through the quarter-wave plate 21 again, is converted from clockwise circularly polarized light to S polarized light, and then re-appears on the third surface 20c of the polarizing beam splitter 20. Incident.

  On the other hand, the measurement light (S-polarized light) related to the first light emitted from the fourth surface 20d of the polarization beam splitter 20 is converted into counterclockwise circularly polarized light by passing through the quarter-wave plate 22, and then the workpiece. Reflected by W. Here, the rotation direction with respect to the traveling direction of the light is maintained. Thereafter, the measurement light related to the first light passes through the quarter-wave plate 22 again, is converted from counterclockwise circularly polarized light to P-polarized light, and then re-appears on the fourth surface 20d of the polarizing beam splitter 20. Incident.

  Here, the reference light (S-polarized light) related to the first light re-entered from the third surface 20c of the polarization beam splitter 20 is reflected leftward in the Z-axis direction at the joint surface 20h, and re-enters from the fourth surface 20d. The measurement light (P-polarized light) according to the first light passes through the bonding surface 20h leftward in the Z-axis direction. Then, the combined light in a state where the reference light and the measurement light related to the first light are combined is emitted from the second surface 20b of the polarization beam splitter 20 as output light.

  The combined light (reference light and measurement light) related to the first light emitted from the second surface 20b of the polarization beam splitter 20 enters the second non-polarization beam splitter 13B. A part of the combined light related to the first light incident leftward in the Z-axis direction with respect to the second non-polarizing beam splitter 13B is transmitted leftward in the Z-axis direction, and the rest is reflected downward in the Y-axis direction. Among these, the combined light (reference light and measurement light) transmitted to the left in the Z-axis direction is incident on the first imaging system 4A. On the other hand, the combined light reflected downward in the Y-axis direction is blocked from traveling by the second optical isolator 12B and becomes discarded light.

  The combined light (reference light and measurement light) related to the first light incident on the first imaging system 4A is first converted into counterclockwise circularly polarized light by the quarter wavelength plate 31A. Then, the measurement light component (P polarization component) is converted into clockwise circular polarization. Here, the counterclockwise circularly polarized light and the clockwise circularly polarized light do not interfere with each other because the rotation directions are different.

  The synthesized light related to the first light subsequently passes through the first polarizing plate 32A, and the reference light component and the measurement light component interfere with each other at a phase corresponding to the angle of the first polarizing plate 32A. Then, the interference light related to the first light is imaged by the first camera 33A.

Next, the optical path of the second light will be described with reference to FIG. As shown in FIG. 4, the second light having the wavelength λ ₂ (linearly polarized light whose polarization direction is inclined by 45 ° with respect to the X-axis direction and the Z-axis direction) is emitted upward from the second light emitting unit 11B in the Y-axis direction.

  The second light emitted from the second light emitting unit 11B passes through the second optical isolator 12B and enters the second non-polarized beam splitter 13B. Part of the second light incident on the second non-polarizing beam splitter 13B is transmitted upward in the Y-axis direction, and the rest is reflected rightward in the Z-axis direction.

  Among these, the second light reflected to the right in the Z-axis direction (linearly polarized light whose polarization direction is inclined by 45 ° with respect to the X-axis direction and the Y-axis direction) is incident on the second surface 20 b of the polarization beam splitter 20. On the other hand, the second light transmitted upward in the Y-axis direction is discarded without entering any optical system or the like.

  Here, if the light to be discarded is used for wavelength measurement or light power measurement as required, the measurement accuracy can be improved by stabilizing the light source.

  The second light incident rightward in the Z-axis direction from the second surface 20b of the polarizing beam splitter 20 is reflected as its S-polarized component downward in the Y-axis direction and emitted as reference light from the third surface 20c, while its P The polarized component is transmitted rightward in the Z-axis direction and is emitted from the fourth surface 20d as measurement light.

  The reference light (S-polarized light) related to the second light emitted from the third surface 20 c of the polarization beam splitter 20 is converted into counterclockwise circularly polarized light by passing through the quarter-wave plate 21, and then the reference surface 23. Reflect on. Here, the rotation direction with respect to the traveling direction of the light is maintained. Thereafter, the reference light related to the second light passes through the quarter-wave plate 21 again, is converted from counterclockwise circularly polarized light to P-polarized light, and then re-appears on the third surface 20 c of the polarizing beam splitter 20. Incident.

  On the other hand, the measurement light (P-polarized light) related to the second light emitted from the fourth surface 20d of the polarization beam splitter 20 is converted into clockwise circularly polarized light by passing through the quarter-wave plate 22, and then the workpiece. Reflected by W. Here, the rotation direction with respect to the traveling direction of the light is maintained. Thereafter, the measurement light related to the second light passes through the quarter-wave plate 22 again, is converted from clockwise circularly polarized light to S-polarized light, and then re-appears on the fourth surface 20d of the polarizing beam splitter 20. Incident.

  Here, the reference light (P-polarized light) related to the second light re-entered from the third surface 20c of the polarization beam splitter 20 passes through the joint surface 20h upward in the Y-axis direction, and re-enters from the fourth surface 20d. The measurement light (S-polarized light) related to the two lights is reflected upward in the Y-axis direction at the bonding surface 20h. Then, the combined light in a state where the reference light and the measurement light related to the second light are combined is emitted from the first surface 20a of the polarization beam splitter 20 as output light.

  The combined light (reference light and measurement light) related to the second light emitted from the first surface 20a of the polarization beam splitter 20 is incident on the first non-polarization beam splitter 13A. A part of the synthesized light related to the second light incident upward in the Y-axis direction with respect to the first non-polarizing beam splitter 13A is transmitted upward in the Y-axis direction, and the rest is reflected rightward in the Z-axis direction. Among these, the combined light (reference light and measurement light) transmitted upward in the Y-axis direction enters the second imaging system 4B. On the other hand, the combined light reflected rightward in the Z-axis direction is blocked by the first optical isolator 12A and becomes discarded light.

  The combined light (reference light and measurement light) related to the second light incident on the second imaging system 4B is first converted into clockwise circularly polarized light by the quarter wavelength plate 31B. Then, the measurement light component (S-polarized component) is converted into counterclockwise circularly polarized light. Here, the counterclockwise circularly polarized light and the clockwise circularly polarized light do not interfere with each other because the rotation directions are different.

  The combined light related to the second light subsequently passes through the second polarizing plate 32B, so that the reference light component and the measurement light component interfere with each other at a phase corresponding to the angle of the second polarizing plate 32B. Then, the interference light related to the second light is imaged by the second camera 33B.

  Next, the procedure of the measurement process executed by the control device 5 will be described in detail with reference to the flowchart of FIG. Hereinafter, when this measurement process is described, the surface of the image sensor 33Aa of the first camera 33A or the surface of the image sensor 33Ba of the second camera 33B is the xy plane, and the optical axis direction orthogonal thereto is the z direction. Will be described. Of course, the coordinate system (x, y, z) and the coordinate system (X, Y, Z) for explaining the entire measuring apparatus 1 are different coordinate systems.

  First, in step S1, processing for acquiring an interference fringe image relating to a predetermined measurement area of the workpiece W is executed. In the present embodiment, four interference fringe images having different phases relating to the first light and four interference fringe images different in phase relating to the second light are acquired here. This will be described in detail below.

  After the workpiece W is installed on the installation unit 24, the transmission axis direction of the first polarizing plate 32A of the first imaging system 4A is set to a predetermined reference position (for example, “0 °”), and the second imaging system 4B The transmission axis direction of the two polarizing plates 32B is set to a predetermined reference position (for example, “0 °”).

  Subsequently, the first light is emitted from the first light projecting system 2A, and at the same time, the second light is emitted from the second light projecting system 2B. As a result, combined light (reference light and measurement light) related to the first light is emitted from the second surface 20b of the polarization beam splitter 20 of the interference optical system 3, and at the same time, from the first surface 20a of the polarization beam splitter 20 The combined light (reference light and measurement light) related to the two lights is emitted.

  The combined light related to the first light emitted from the second surface 20b of the polarization beam splitter 20 is imaged by the first imaging system 4A, and at the same time, the second light emitted from the first surface 20a of the polarization beam splitter 20 is converted into the second light. Such synthesized light is imaged by the second imaging system 4B.

  Here, since the transmission axis directions of the first polarizing plate 32A and the second polarizing plate 32B are each set to “0 °”, the first camera 33A has an interference fringe of the phase “0 °” related to the first light. An image is captured, and the second camera 33B captures an interference fringe image of the phase “0 °” related to the second light.

  Then, image data captured from each of the cameras 33 </ b> A and 33 </ b> B is output to the control device 5. The control device 5 stores the input image data in the image data storage device 54.

  Next, the control device 5 performs a switching process between the first polarizing plate 32A of the first imaging system 4A and the second polarizing plate 32B of the second imaging system 4B. Specifically, the first polarizing plate 32A and the second polarizing plate 32B are rotated and displaced to positions where the transmission axis direction is “45 °”.

  When the switching process ends, the control device 5 performs the second imaging process similar to the series of the first imaging process. That is, the control device 5 irradiates the first light from the first light projecting system 2 </ b> A and at the same time irradiates the second light from the second light projecting system 2 </ b> B and emits the second light from the second surface 20 b of the polarization beam splitter 20. The combined light related to one light is imaged by the first imaging system 4A, and simultaneously, the combined light related to the second light emitted from the first surface 20a of the polarization beam splitter 20 is imaged by the second imaging system 4B. As a result, an interference fringe image having the phase “90 °” related to the first light is acquired, and an interference fringe image having the phase “90 °” related to the second light is captured.

  Thereafter, the same imaging process as the first and second imaging processes is repeated twice. That is, the third imaging process is performed in a state where the transmission axis directions of the first polarizing plate 32A and the second polarizing plate 32B are set to “90 °”, and an interference fringe image of the phase “180 °” related to the first light is obtained. In addition to the acquisition, an interference fringe image of the phase “180 °” related to the second light is acquired.

  Thereafter, the fourth imaging process is performed in a state where the transmission axis directions of the first polarizing plate 32A and the second polarizing plate 32B are set to “135 °”, and an interference fringe image of the phase “270 °” related to the first light is obtained. In addition to the acquisition, an interference fringe image of phase “270 °” related to the second light is acquired.

  As described above, by performing the imaging process four times, all the image data (four kinds of interference fringe images related to the first light, and the first image light necessary for performing the measurement related to the predetermined measurement region of the workpiece W) A total of eight interference fringe images consisting of four interference fringe images relating to two lights) can be acquired.

  In subsequent step S2, the control device 5 executes a process of acquiring complex amplitude data Eo (x, y) of light on the surfaces of the imaging elements 33Aa and 33Ba. Specifically, based on the four types of interference fringe images related to the first light and the four types of interference fringe images related to the second light stored in the image data storage device 54, the first light and the second light respectively. The complex amplitude data Eo (x, y) of light on the surfaces of the imaging elements 33Aa and 33Ba is acquired.

The interference fringe intensity at the same coordinate position (x, y) of the four interference fringe images related to the first light or the second light, that is, the luminances I ₁ (x, y), I ₂ (x, y), I ₃ ( x, y) and I ₄ (x, y) can be expressed by the following relational expression [Formula 1].

  Here, Δφ (x, y) represents a phase difference based on the optical path difference between the measurement light and the reference light at the coordinates (x, y). A (x, y) represents the amplitude of the interference light, and B (x, y) represents the bias. However, since the reference light is uniform, Δφ (x, y) represents “the phase of the measurement light” and A (x, y) represents “the amplitude of the measurement light”. Become.

  Therefore, the phase Δφ (x, y) of the measurement light that has reached the surfaces of the image pickup devices 33Aa and 33Ba can be obtained by the following relational expression [Formula 2] based on the relational expression [Formula 1].

  Further, the amplitude A (x, y) of the measurement light that has reached the surfaces of the image sensors 33Aa and 33Ba can be obtained by the following relational expression [Formula 3] based on the relational expression [Formula 1].

  Then, complex amplitude data Eo (x, y) on the surfaces of the image sensors 33Aa and 33Ba is calculated from the phase Δφ (x, y) and the amplitude A (x, y) based on the following relational expression [Formula 4]. be able to. Here, i represents an imaginary unit.

  In subsequent step S <b> 3, the control device 5 executes a process of acquiring complex amplitude data at a plurality of positions in the z direction for a part of specific areas preset in a predetermined measurement area of the workpiece W. The first data acquisition unit in the present embodiment is configured by the function of executing a series of processes related to steps S2 and S3.

  The “specific area” is an area arbitrarily set in order to investigate the position of the workpiece W in the z direction in advance. Hereinafter, the “specific region” is referred to as “z position survey region V” (see FIG. 7). For example, when the workpiece W is a wafer substrate 100 as shown in FIG. 8, the pattern portion 102 that can serve as a reference plane for measuring the height of the bump 101 can be set as the z position inspection region V.

  Hereinafter, the process of step S3 will be described in detail. First, a method for acquiring unknown complex amplitude data at different positions in the z direction from known complex amplitude data at predetermined positions in the z direction will be described.

  Here, two coordinate systems (an xy coordinate system and a ξ-η coordinate system) separated by a distance d in the z direction are considered. Then, the xy coordinate system is set to z = 0, the complex amplitude data of the known light in the xy coordinate system is represented by Eo (x, y), and the ξ-η plane separated from the xy plane by a distance d If the complex amplitude data of the unknown light at E is expressed as Eo (ξ, η), the relationship shown in the following [Formula 5] is obtained. Here, λ represents a wavelength.

  Solving this for Eo (ξ, η) yields [Equation 6] below.

  In the present embodiment, as shown in FIGS. 6 and 7, the z position investigation region on the workpiece W is based on the complex amplitude data Eo (x, y) on the image pickup devices 33 </ b> Aa and 33 </ b> Ba obtained in step S <b> 2. For V, complex amplitude data EoL0 (ξ, η), EoL1 (ξ, η) at positions where the distance L in the z direction from the surfaces of the image pickup devices 33Aa, 33Ba is L0, L1, L2,. .., EoLn (ξ, η) is acquired.

  In subsequent step S <b> 4, the control device 5 executes a process of acquiring intensity (luminance) images at a plurality of positions in the z direction for the z position survey region V on the workpiece W. The function for executing the processing of step S4 constitutes the image acquisition means in this embodiment.

  Specifically, intensity images are acquired from the complex amplitude data EoL0 (ξ, η), EoL1 (ξ, η),..., EoLn (ξ, η) acquired in step S3. When the complex amplitude data on the ξ-η plane is expressed by Eo (ξ, η), the intensity image I (ξ, η) on the ξ-η plane can be obtained by the following relational expression [Equation 7]. .

  In subsequent step S5, the control device 5 executes processing for determining the position of the workpiece W in the z direction. The function for executing the processing of step S5 constitutes the position determining means in this embodiment.

  Specifically, the position of the z position survey region V in the z direction is determined based on the plurality of intensity images related to the z position survey region V acquired in step S4. Hereinafter, a method for determining the position of the z position investigation region V from the contrast of the intensity image will be described.

  For example, as shown in FIG. 7, a predetermined range Q in the z direction in which the workpiece W can exist is divided by measurement range intervals for height measurement, and distances L in the z direction from the surfaces of the image sensors 33Aa and 33Ba are L0, L1, and L2. ,..., Ln separated positions (z = L0, L1,..., Ln), z position survey regions at each position in the z direction (z = L0, L1,..., Ln). For the V intensity image, the luminance contrast between the “z position survey region V” and the “other portion” is obtained. Subsequently, a position (z = Lm) where an intensity image with the highest contrast is obtained is extracted. Then, three-dimensional measurement is performed based on the complex amplitude data EoLm (ξ, η) at this position (z = Lm), and the height information of the z position survey region V is acquired. Based on this, the absolute position of the z position survey region V in the z direction is acquired by “position information of the intensity image (z = Lm)” + “height information of the z position survey region V”.

  In addition, as a method of determining the position of the z position survey region V, not only the method of obtaining from the above-described contrast of the intensity image but also other methods may be adopted. For example, a method of obtaining from the luminance of the intensity image may be adopted.

  In this method, the luminance image takes advantage of the property that it is strongest on the surface where the object is actually present. Specifically, in the intensity image of the z position investigation region V at each position in the z direction (z = L0, L1,..., Ln), the average luminance of the z position investigation region V is obtained. Subsequently, a position (z = Lm) where an intensity image with the highest average luminance is obtained is extracted. Thereafter, similarly to the above, three-dimensional measurement is performed based on the complex amplitude data EoLm (ξ, η) at this position (z = Lm), and the height information of the z position survey region V is acquired. Based on this, the absolute position of the z position survey region V in the z direction is acquired by “position information of the intensity image (z = Lm)” + “height information of the z position survey region V”.

  In subsequent step S6, the control device 5 acquires complex amplitude data of the entire measurement region at the position in the z direction of the workpiece W (z position investigation region V) determined in step S5. The function of executing the processing in step S6 constitutes the second data acquisition unit in the present embodiment.

  In subsequent step S7, the control device 5 executes a three-dimensional measurement process. The function for executing the processing of step 7 constitutes the measurement execution means in this embodiment.

  Specifically, from the complex amplitude data Eo (ξ, η) of the entire measurement region obtained in step S6, the phase φ (ξ, η) of the measurement light and the measurement based on the following relational expression [8] The light amplitude A (ξ, η) is calculated.

  The phase φ (ξ, η) of the measurement light can be obtained by the following relational expression [Equation 9].

  The amplitude A (ξ, η) of the measurement light can be obtained by the following relational expression [Equation 10].

  Thereafter, phase-height conversion processing is performed to calculate height information z (ξ, η) that three-dimensionally shows the uneven shape of the surface of the workpiece W.

  The height information z (ξ, η) can be calculated by the following equation [11].

Here, when measurement is performed using two types of light having different wavelengths (wavelengths λ ₁ and λ ₂ ), the measurement is the same as the measurement using the light having the combined wavelength λ ₀ . Then, the measurement range and thus to increase the lambda _0/2. The synthetic wavelength λ ₀ can be expressed by the following formula (M1).

λ ₀ = (λ ₁ × λ ₂ ) / (λ ₂ −λ ₁ ) (M1)
However, it is assumed that λ ₂ > λ ₁ .

For example, when λ ₁ = 1500 nm and λ ₂ = 1503 nm, from the above formula (M1), λ ₀ = 751.500 μm and the measurement range is λ ₀ /2=375.750 μm.

More specifically, in the present embodiment, first, the luminances I ₁ (x, y), I ₂ (x, y), I ₃ (x, y) of four kinds of interference fringe images related to the first light of wavelength λ ₁ are used. ), I ₄ (x, y) (see [Equation 1] above), the phase φ ₁ (ξ, η) of the measurement light related to the first light at the coordinates (ξ, η) on the workpiece W surface Can be calculated (see [Equation 9] above).

  Under the measurement related to the first light, the height information z (ξ, η) at the coordinates (ξ, η) can be expressed by the following formula (M2).

z (ξ, η) = d ₁ (ξ, η) / 2
_{= [Λ 1 × φ 1 (} ξ, η) / 4π] + [m 1 (ξ, η) × λ 1/2] ··· (M2)
Here, d ₁ (ξ, η) represents an optical path difference between the measurement light related to the first light and the reference light, and m ₁ (ξ, η) represents a fringe order related to the first light.

Therefore, the phase φ ₁ (ξ, η) can be expressed by the following formula (M2 ′).

φ ₁ (ξ, η) = (4π / λ ₁ ) × z (ξ, η) −2πm ₁ (ξ, η) (M2 ′)
Similarly, the luminances I ₁ (x, y), I ₂ (x, y), I ₃ (x, y), I ₄ (x, y) of the four kinds of interference fringe images related to the second light of wavelength λ ₂ ) (See [Expression 1] above), the phase φ ₂ (ξ, η) of the measurement light related to the second light at the coordinates (ξ, η) on the workpiece W surface can be calculated (see above [ (See Equation 9]).

  Under the measurement of the second light, the height information z (ξ, η) at the coordinates (ξ, η) can be expressed by the following formula (M3).

z (ξ, η) = d ₂ (ξ, η) / 2
_{= [Λ 2 × φ 2 (} ξ, η) / 4π] + [m 2 (ξ, η) × λ 2/2] ··· (M3)
Here, d ₂ (ξ, η) represents the optical path difference between the measurement light related to the second light and the reference light, and m ₂ (ξ, η) represents the fringe order related to the second light.

Therefore, the phase φ ₂ (ξ, η) can be expressed by the following formula (M3 ′).

φ ₂ (ξ, η) = (4π / λ ₂ ) × z (ξ, η) −2πm ₂ (ξ, η) (M3 ′)
Here, the fringe order m ₁ (ξ, η) related to the first light of wavelength λ ₁ and the fringe order m ₂ (ξ, η) related to the second light of wavelength λ ₂ are two types of light (wavelengths). (λ ₁ , λ ₂ ) can be obtained based on the optical path difference Δd and the wavelength difference Δλ. The optical path difference Δd and the wavelength difference Δλ can be expressed as the following formulas (M4) and (M5), respectively.

Δd = (λ ₁ × φ ₁ −λ ₂ × φ ₂ ) / 2π (M4)
Δλ = λ ₂ −λ ₁ (M5)
However, it is assumed that λ ₂ > λ ₁ .

In the measurement range of the two combined wavelengths λ ₀ , the relationship between the fringe orders m ₁ and m ₂ is divided into the following three cases. For each case, the fringe orders m ₁ (ξ, η), m _{2 The} formula for determining (ξ, η) is different. Here, for example, a case where the fringe order m ₁ (ξ, η) is determined will be described. Of course, the fringe order m ₂ (ξ, η) can also be obtained by the same method.

For example, in the case of “φ ₁ −φ ₂ <−π”, “m ₁ −m ₂ = −1”. In such a case, m ₁ can be expressed as the following formula (M6).

m ₁ = (Δd / Δλ) − (λ ₂ / Δλ)
= (Λ ₁ × φ ₁ −λ ₂ × φ ₂ ) / 2π (λ ₂ −λ ₁ ) −λ ₂ / (λ ₂ −λ ₁ ) (M6)
In the case of “−π <φ ₁ −φ ₂ <π”, “m ₁ −m ₂ = 0”. In such a case, m ₁ can be expressed as the following formula (M7).

m ₁ = Δd / Δλ
= (Λ ₁ × φ ₁ −λ ₂ × φ ₂ ) / 2π (λ ₂ −λ ₁ ) (M7)
In the case of “φ ₁ −φ ₂ > π”, “m ₁ −m ₂ = + 1”, and in such a case, m ₁ can be expressed as the following formula (M8).

m ₁ = (Δd / Δλ) + (λ ₂ / Δλ)
= (Λ ₁ × φ ₁ −λ ₂ × φ ₂ ) / 2π (λ ₂ −λ ₁ ) + λ ₂ / (λ ₂ −λ ₁ ) (M8)
Obtaining height information z (ξ, η) from the above formulas (M2) and (M3) based on the fringe order m ₁ (ξ, η) or m ₂ (ξ, η) obtained in this way. Can do.

  For example, when the workpiece W is the wafer substrate 100 (see FIGS. 8 and 9) and the bump 101 is the measurement target, the height HB of the bump 101 with respect to the pattern portion 102 that is the measurement reference plane is the absolute height ho of the bump 101. From this, it can be obtained by subtracting the absolute height hr of the pattern portion 102 around the bump 101 [HB = ho−hr]. Here, as the absolute height hr of the pattern unit 102, for example, an absolute height of an arbitrary point on the pattern unit 102, an average value of absolute heights in a predetermined range on the pattern unit 102, or the like can be used. Further, “the absolute height ho of the bump 101” and “the absolute height hr of the pattern portion 102” can be obtained as the height information z (ξ, η).

  Then, the measurement result (height information) of the workpiece W obtained in this way is stored in the calculation result storage device 55 of the control device 5.

  As described above in detail, in this embodiment, first, not only the entire measurement area of the workpiece W, but only a part of the z position investigation areas V set in advance in the measurement area, the complex amplitudes at a plurality of positions in the optical axis direction. Data is acquired, and based on this data, the position of the optimum work W (z position investigation region V) that is in focus is searched and determined. Thereafter, complex amplitude data is obtained for the entire measurement area of the workpiece W at such a position, and measurement related to the measurement area is performed.

  As a result, it is possible to reduce the load required for processing for acquiring data necessary for performing measurement related to the measurement region, and it is possible to reduce the time required for the processing. As a result, measurement accuracy can be improved and measurement efficiency can be improved.

  Furthermore, in the present embodiment, the z-direction position of the workpiece W (z position survey area V) is specified, and the complex amplitude data of the entire measurement area at the position is acquired and measured. Compared to a configuration in which optimum data is extracted from complex amplitude data acquired at a plurality of intervals (measurement ranges), more optimal and accurate data focused on the workpiece W (z position survey region V). Can be obtained. As a result, the measurement accuracy can be further improved.

In the present embodiment, the first light having the wavelength λ ₁ is incident from the first surface 20 a of the polarizing beam splitter 20 and the second light having the wavelength λ ₂ is incident from the second surface 20 b of the polarizing beam splitter 20. Therefore, the reference light and the measurement light according to the first light and the reference light and the measurement light according to the second light are respectively divided into different polarization components (P-polarized light or S-polarized light). The one light and the second light are separately emitted from the polarization beam splitter 20 without interfering with each other. That is, it is not necessary to separate the light emitted from the polarization beam splitter 20 into the first light and the second light using a predetermined separating means.

  As a result, two types of light having close wavelengths can be used as the first light and the second light, and the measurement range related to three-dimensional measurement can be further expanded. In addition, the imaging of the output light related to the first light and the imaging of the output light related to the second light can be performed simultaneously, so that the overall imaging time can be shortened and the measurement efficiency can be improved.

  In addition, it is not limited to the description content of the said embodiment, For example, you may implement as follows. Of course, other application examples and modification examples not illustrated below are also possible.

  (A) The workpiece W as an object to be measured is not limited to the wafer substrate 100 exemplified in the above embodiment. For example, a printed circuit board on which cream solder is printed may be used as the workpiece W (object to be measured).

  Further, a bump inspection apparatus or a solder printing inspection apparatus provided with inspection means for inspecting the quality of a bump or cream solder to be measured according to a predetermined quality determination criterion may be configured to include the measurement device 1. .

  (B) In the above embodiment, the predetermined measurement area of the workpiece W is not particularly mentioned, but the entire workpiece W may be set as the measurement area according to the size of the workpiece W, or one of the workpieces W may be set. A part may be set as a measurement region.

  For example, in the above-described embodiment, the installation unit 24 on which the workpiece W is installed is configured to be displaceable, the surface of the workpiece W is divided into a plurality of measurement regions, and the shape of each measurement region is measured while sequentially moving each measurement region. The configuration may be such that the shape of the entire workpiece W is measured in multiple steps.

  (C) The configuration of the interference optical system (predetermined optical system) is not limited to the above embodiment. For example, in the above embodiment, the optical configuration of the Michelson interferometer is adopted as the interference optical system. However, the present invention is not limited to this, and incident light such as a Mach-Zehnder interferometer or an optical configuration of a Fizeau interferometer is used as reference light. Other optical configurations may be adopted as long as the workpiece W is measured by being divided into the measurement light.

  (D) In the above embodiment, the workpiece W is measured using two types of light having different wavelengths. However, the configuration is not limited to this, and the workpiece W is measured using only one type of light. It is good also as composition which performs.

  When two types of light having different wavelengths are used, the interference optical is not limited to the configuration according to the above-described embodiment, but is combined with the first wavelength light and the second wavelength light in the same manner as the conventional measurement apparatus. The interference light emitted from the system is separated by a predetermined optical separation means (such as a dichroic mirror) to obtain interference light related to the first wavelength light and interference light related to the second wavelength light. The workpiece W may be measured based on an interference fringe image obtained by individually capturing the interference light related to each wavelength light.

  In addition, two types of light emitted from two light sources having different wavelengths are superimposed on each other and incident on the interference optical system, and the light emitted from the two light sources is wavelength-separated by an optical separation means, and is converted into light of each wavelength described above. A configuration in which such interference light is individually imaged may be combined with the above-described embodiment, and the workpiece W may be measured using three or more types of light having different wavelengths.

(E) The configuration of the light projecting systems 2A and 2B is not limited to the above embodiment. For example, in the above embodiment, light having a wavelength λ ₁ = 1500 nm is irradiated from the first light projecting system 2A, and light having a wavelength λ ₂ = 15033 nm is irradiated from the second light projecting system 2B. The wavelength of light is not limited to this. However, in order to widen the measurement range, it is preferable to reduce the wavelength difference between the two lights.

  (F) In the above-described embodiment, four types of interference fringe images having phases different from each other by 90 ° are obtained for the first light and the second light. It is not limited to. For example, a configuration may be adopted in which three types of interference fringe images having different phases by 120 ° (or 90 °) are acquired and the workpiece W is measured.

  (G) In the above-described embodiment, the polarizing plates 32A and 32B configured so that the transmission axis direction can be changed are employed as the phase shift unit. However, the configuration of the phase shift unit is not limited to this. .

  For example, a configuration in which the optical path length is physically changed by moving the reference surface 23 along the optical axis by a piezo element or the like may be employed.

  However, in such a configuration and the above-described embodiment, since it takes a certain time to acquire all the interference fringe images necessary for the measurement, not only the measurement time is lengthened, but also affected by the fluctuation and vibration of the air. Therefore, there is a possibility that the measurement accuracy is lowered.

  On the other hand, for example, in the first imaging system 4A, a spectral means (such as a prism) that divides the combined light (reference light component and measurement light component) related to the first light transmitted through the quarter-wave plate 31A into four lights. In addition to the first polarizing plate 32A, as the phase shift means, there are provided filter means for giving different phase differences to the four lights emitted from the spectroscopic means, and transmitted through the filter means 4 A configuration may be adopted in which two lights are simultaneously imaged by the first camera 33A (or a plurality of cameras). Of course, the second imaging system 4B may have the same configuration.

  With this configuration, all the interference fringe images necessary for measurement can be acquired simultaneously. That is, a total of eight types of interference fringe images related to two types of light can be acquired simultaneously. As a result, the measurement accuracy can be improved and the overall imaging time can be greatly shortened, and the measurement efficiency can be dramatically improved.

  (H) In the above embodiment, in the process of determining the position of the workpiece W (z position survey region V) in the z direction, complex amplitude data or the like is obtained at the measurement range interval of the height measurement. For example, the configuration may be such that complex amplitude data or the like is acquired at the focusing range interval.

  (I) In the said embodiment, it becomes the structure which performs three-dimensional measurement in step S7 based on the complex amplitude data of the whole measurement area | region obtained in step S6. Instead of this, or in addition to this, an intensity image of the entire measurement region may be acquired based on the complex amplitude data of the entire measurement region obtained in step S6, and two-dimensional measurement may be performed.

  When only two-dimensional measurement is performed in step S7, based on the measurement result, for example, the positional deviations Δx and Δy, the outer diameter D, the area S, and the like of the bump 101 (see FIG. 10) to be measured are It is possible to perform a two-dimensional inspection for determining whether the bump 101 is good or not by comparing with a preset reference value and determining whether the comparison result is within an allowable range.

  In addition, when both the two-dimensional measurement and the three-dimensional measurement are performed in step S7, the place where the bump 101 to be measured exists is specified based on the result of the two-dimensional measurement (two-dimensional inspection). It is possible to perform a comprehensive inspection combining a plurality of types of measurement, such as performing a three-dimensional inspection or mapping an intensity image to three-dimensional data obtained by three-dimensional measurement.

  (J) In the above embodiment, a camera provided with a lens is used. However, a lens is not always necessary, and even if a camera without a lens is used, according to the above embodiment, a focused image is obtained. It can be obtained by calculation.

  (K) In the above embodiment, the z-direction position of the workpiece W (z-position survey area V) is specified, and the complex amplitude data of the entire measurement area at the position is acquired and measured. The z-direction position for acquiring the complex amplitude data of the entire region is not limited to this. For example, the measurement may be performed by acquiring complex amplitude data of the entire measurement region at the position (z = Lm) where the most focused intensity image is obtained.

  (L) In the wafer substrate 100 exemplified in the above embodiment, the pattern portion 102 serving as the reference surface for the height measurement of the bump 101 is set as the z position inspection region V, but the z position inspection region V is not necessarily the reference surface. It does not have to be a part that can be, and may be another part.

  (M) Although not particularly mentioned in the above embodiment, the z position survey region V may be set at a plurality of locations. Since there are a plurality of z position survey areas V, it becomes easier to find a more optimal position where the complex amplitude data of the entire measurement area should be acquired.

  DESCRIPTION OF SYMBOLS 1 ... Measuring apparatus, 2A ... 1st light projection system, 2B ... 2nd light projection system, 3 ... Interference optical system, 4A ... 1st imaging system, 4B ... 2nd imaging system, 5 ... Control apparatus, 11A ... 1st Light emitting unit, 11B ... second light emitting unit, 12A ... first optical isolator, 12B ... second optical isolator, 13A ... first non-polarized beam splitter, 13B ... second non-polarized beam splitter, 20 ... polarized beam splitter, 20a ... 1st surface, 20c ... 3rd surface, 20b ... 2nd surface, 20d ... 4th surface, 21, 22 ... 1/4 wavelength plate, 23 ... Reference surface, 24 ... Installation part, 31A ... 1/4 wavelength plate, 31B ... 1/4 wavelength plate, 32A ... first polarizing plate, 32B ... second polarizing plate, 33A ... first camera, 33B ... second camera, 33Aa, 33Ba ... imaging device, 100 ... wafer substrate, 101 ... bump, 102: Pattern portion, V: z position survey area, W: Wa Click.

Claims (7)

The incident predetermined light is divided into two lights, one light can be irradiated as a measurement light on the object to be measured, and the other light can be irradiated as a reference light on the reference surface. A predetermined optical system capable of emitting;
Irradiating means capable of emitting predetermined light incident on the predetermined optical system;
Imaging means capable of imaging output light emitted from the predetermined optical system;
An image processing unit comprising: an image processing unit capable of executing a measurement related to a predetermined measurement region of the measurement object based on an interference fringe image obtained by the imaging unit;
The image processing means includes
Based on the interference fringe image obtained by the imaging means, the complex amplitude data at a predetermined position in the optical axis direction is determined at least within a predetermined range in the optical axis direction for a specific area preset in the measurement area. First data acquisition means for acquiring a plurality of data for each interval;
Image acquisition means for acquiring a plurality of intensity images for each predetermined interval relating to the specific area from a plurality of complex amplitude data for the predetermined area relating to the specific area acquired by the first data acquisition means;
Position determining means for determining a predetermined position in the optical axis direction based on the plurality of intensity images acquired by the image acquiring means;
Second data acquisition means for acquiring complex amplitude data at the position determined by the position determination means for the entire measurement region;
A measurement apparatus comprising: a measurement execution unit that executes measurement related to the measurement region based on the complex amplitude data acquired by the second data acquisition unit.   The measurement apparatus according to claim 1, wherein the position determination unit determines a position in the optical axis direction of the specific region based on the plurality of intensity images acquired by the image acquisition unit.   The measurement device according to claim 2, wherein the specific region is a region serving as a reference when performing measurement in the optical axis direction related to the measurement region.   The measuring device according to claim 1, wherein the specific region is set at a plurality of locations. Phase shift means for providing a relative phase difference between the reference light and the measurement light;
The image processing means includes
Based on a plurality of interference fringe images obtained by imaging the output light phase-shifted by the phase-shifting means by the imaging means, it is possible to perform measurement related to a predetermined measurement region of the object to be measured. The measuring device according to claim 1, wherein the measuring device is configured as described above. The irradiation means includes
First irradiating means capable of emitting first light including polarized light having a first wavelength, which is incident on the predetermined optical system;
A second irradiating means capable of emitting second light including polarized light of a second wavelength that is incident on the predetermined optical system;
The imaging means includes
First imaging means capable of imaging output light related to the first light emitted from the predetermined optical system by making the first light incident on the predetermined optical system;
And second imaging means capable of imaging the output light related to the second light emitted from the predetermined optical system when the second light is incident on the predetermined optical system. The measuring device according to claim 1.   7. The measuring apparatus according to claim 1, wherein the object to be measured is a wafer substrate on which bumps are formed.

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